Caitlin: Last week, NASA launched a football-stadium-sized balloon from Wanaka, New Zealand... for science! This is the fourth and hopefully-longest test flight of this balloon. It’ll ideally circle the globe for around 100 days, breaking its 2009 record of 54 days. And it’s carrying about a metric ton of scientific instruments, to monitor the stratosphere and look deep into our galaxy.

For years, NASA’s Balloon Program has been collaborating with the company Orbital ATK to create a super pressure balloon, or SPB. It’s made of 22 acres of a strong, durable plastic film, and has a volume of 532,000 cubic meters. The balloon team has been preparing for its fourth official launch at the Wanaka Airport since March of this year, and after five liftoff attempts that were scrapped due to weather conditions, it finally flew on May 17th.

It only took a couple of hours for the balloon reach its highest altitude of 33.5 kilometers, in the stratosphere. And it’s flying around the world at middle-latitudes in the southern hemisphere, hopefully avoiding any rips because of the changes in air pressure that come from daily changes in temperature. The SPB first moved westward through southern Australia, before being pushed eastward by stratospheric winds. Now, scientists predict that it’ll start circumnavigating the Earth once every couple of weeks, thanks to natural wind patterns.

The balloon is carrying a bunch of research, tracking, and communication technology that weighs about 1,025 kilograms. One of those instruments is the Compton Spectrometer and Imager, or COSI, a gamma ray telescope, which has flown with an SPB before. The COSI team, which is based out of UC Berkeley, plans to use the telescope to study the evolution of matter -- how different atoms in the universe formed; where positrons -- which are like electrons with a positive charge -- came from; and how gamma rays are moving through the galaxy.

Another mission aboard the SPB is the Carolina Infrasound instrument, which was developed by researchers at the University of North Carolina at Chapel Hill. As the name suggests, it’s designed to detect infrasound -- sounds that are too low-pitched for us to hear. This instrument only weighs 3 kilograms and includes three infrasound microphones, a data collector, and a power supply. And it’s designed to to map out acoustic wave field activity in the stratosphere -- how different sound waves are moving through all the gases in that layer, which can’t be fully detected with ground-based devices. These kinds of maps could be used to detect nuclear blasts from a distance or monitor heat in different regions of the atmosphere. Because of tracking instruments on the balloon, you can actually watch the flight path of the balloon yourself! The link is in the description.

But NASA’s not only measuring things on Earth. New radar data from Mars’s polar ice caps that was just published yesterday in the journal Science suggest that the Martian climate has been shifting away from an ice age for nearly 400,000 years. This is something that was theorized in models of the Red Planet, but wasn’t supported by observational data... until now.

A team of researchers analyzed data from Mars Reconnaissance Orbiter, which was launched in 2005, and is now on its second extended mission monitoring the atmosphere and surface of Mars. Using the orbiter’s Shallow Radar instrument, they observed the layers of water ice and rock at the Martian poles. They discovered these geologic features called unconformities, which are layers of rock that are next to each other, but very different in age.

Unconformities happen when there’s some erosion, and then new sediments are deposited on top -- which can be because of changes in climate. And the researchers found that in the past 370,000 years or so, the volume of the north polar layered deposits of ice and other dust has grown by about 80,000 cubic kilometers, or a layer about 55 centimeters thick. Which tells them that the planet is leaving an ice age.

Normally, kind of like on Earth right now, the colder regions of Mars are concentrated in the ice caps at the North and South poles. But during a Martian ice age, there’s more ice near the middle-latitudes of the Red Planet. There’s a wider range of ice coverage, but the poles are actually warmer than usual. So ice builds up at the poles as an ice age ends.

Understanding how the layers ice and rock on Mars are changing helps us understand its changing climate -- and might even help us learn how it went from being habitable to unhabitable. By studying Mars, scientists hope to better predict how the Earth’s climate might change over hundreds of thousands of years.

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